Or to make them relate more to you, think about it. Why are Caucasians so much more taller and stronger than those from the third-world places? Because back in their history, they had many wars, and the weak ones were flushed out, leaving only the strong ones to pass their genes on to the next generations. The Africans were forced to work as slaves, and the weak ones died out, leaving only the strongest ones to pass their genes on to the next generations. Which is why many black people are muscular (Usain Bolt, for example) and strong. It's their genes.
And take a look at ... maybe Malaysia? They're apparently famous for being a slightly lazy bunch of people
Why? Because they never really fought many wars. Their natives coexisted harmoniously for thousands of years, and of course with the lack of war, the weak ones continue to flourish.
Sorry if this insulted anyone. Had to role-play this Sith Lord a bit.
African-Americans are just as big and strong as Caucasians in America. Malsaian ancestry people born and raised in America are just as capable as Caucasians in America. Prior to the Victorian age, the average European was 4' 11" tall. (1.5M) When the pilgrams first came to america, they considered the native americans giants.
This disproves your theory. A better explanation is diet and nutrition. I saw a picture of two
IDENTICAL African twins. One was raised in an catholic orphanage, the other in an African village the
identical twin that got a better diet was at least 10" (25 CM) taller than the other.